Fluid ejection devices are used to eject fluids. Inkjet printing systems are one type of fluid ejection device. Often, an inkjet printing system includes an inkjet printhead die that includes a semiconductor substrate having one or more arrays of firing nozzles and circuitry for addressing the nozzles. In some fluid ejection devices, such as in inkjet printhead systems, the semiconductor die or chip includes non-volatile memory, such as fuses.
In recent years, electronically programmable read-only memory (EPROM) devices have been developed. These devices include a memory cell at each row and column intersection. Each memory cell includes a floating gate and a control gate or input gate. In an un-programmed memory cell, the floating gate has no charge, which causes the threshold voltage to be low. In a programmed memory cell, the floating gate is charged with electrons and the threshold voltage is higher. A memory cell having a lower threshold voltage is one logic value and a memory cell having a higher threshold voltage is the other logic value.